Anchor assembly for strength member of communication cable

ABSTRACT

An improved interconnection between a structural member and a shielded coaxial cable reduces the possibility of there being created uneven, failure inducing, tensile stresses. An elongate fitting member is provided with a passageway for electrical or fiber-optic conductors and is sized to be fitted within the coaxially disposed braided shielding. A cylindrically-shaped retaining member is shaped with a bore having dimensions slightly in excess of the combined diameter of the fitting member and thickness of the braided shielding. As the cable is brought under tension, a slight constriction of the braided shielding occurs. This constriction results in a uniform gripping force along the length of the fitting member. A radially extending rim on the innermost extension of the fitting member is brought to bear against the innermost extension of the retaining member and the cable is anchored in place. The coaction of the aforedescribed elements ensures high reliability since there are uniform stresses exerted and no failure-inducing load concentrations.

United States Patent Campbell ANCHOR ASSEMBLY FOR STRENGTH MEMBER OFCOMMUNICATION CABLE [75] Inventor: Robyn M. Campbell, San Diego,

Calif.

[73] Assignee: The United States of America as represented by theSecretary of the Navy, Washington, DC.

[22] Filed: Dec. 17, 1973 [21] Appl. No.: 425,357

[52] US. Cl 174/65 R; 174/89; 350/96 C [51] Int. Cl H02g 3/06 [58] Fieldof Search 174/35 C, 65 R, 65 SS, 174/70 R, 75 C, 89, 151;:150/96 B, 96 C[56] References Cited UNITED STATES PATENTS 2.762.025 9/1956 Melcher174/35 C X 3,142.721 7/1964 Long 174/89 X 3,368,025 2/1968 Burdett etal. 174/75 C FORElGN PATENTS OR APPLICATIONS l.l9l,748 4/1959 France174/89 Primary ExaminerLaramie E. Askin Attorney, Agent. or Firm-RichardS. Sciascia; Ervin F Johnston; Thomas Glenn Keough [57] ABSTRACT Animproved interconnection between a structural member and a shieldedcoaxial cable reduces the possibility of there being created uneven.failure inducing. tensile stresses. An elongate fitting member is provided with a passageway for electrical or fiber-optic conductors and issized to be fitted within the coaxi ally disposed braided shielding. Acylindrically-shaped retaining member is shaped with a bore havingdimensions slightly in excess of the combined diameter of the fittingmember and thickness of the braided shielding. As the cable is broughtunder tension, a slight constriction of the braided shielding occurs.This constriction results in a uniform gripping force along the lengthof the fitting member. A radially extending rim on the innermostextension of the fitting member is brought to bear against the innermostextension of the retaining member and the cable is anchored in place.The coaction of the aforedeseribed elements ensures high reliabilitysince there are uniform stresses exerted and no failure-inducing loadconcentrations.

2 Claims, 2 Drawing Figures ANCHOR ASSEMBLY FOR STRENGTH MEMBER OFCOMMUNICATION CABLE STATEMENT OF GOVERNMENT INTEREST The inventiondescribed herein may be manufactured and used by or for the Governmentof the United States of America for governmental purposes without thepayment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION Routinely. engineers and technicians provideauxili ary supporting lines for fiber-optics or electrical cables. Insome instances, the added weight of the auxiliary line in a datatransfer or power supply system has seri ously impaired the systemsability to function properly. Particularly in the case of an electricalor an electronic system, the added bulk and weight of coaxial cableshave increased this problem. While the coaxial cables avoid the problemsassociated with cross talk and the data transfer capability is increasedsubstantially, excessive weight remains a primary design problem.Noteworthy attempts have been made to meet this problem by includingappropriately configured connectors at suitable intervals and atopposite ends of the coaxial link. Most of these connectors use clampingarrangements or a variety of flange-and-cone combinations to couple thebraided shields to structural members. In all of these connectors thereis created certain critical areas where the braided shielding issubjected to concentrated tensile or torsional stresses. Therefore,along these areas it is not uncommon for failure to occur, especiallywhere towed sensors or suspended loads need be borne. Furthermore, thoseconnectors using above referred to approaches and also seeking to avoidthe creation of high-stress areas on the shielding are needlesslycomplex. Such connectors are fabricated from a number of machinedcomponents and, consequently, their per unit cost is raised and theirreliability is impaired. There is a continuing need in thestate-ofthe-art for an uncomplicated coaxial cable connector which isinexpensive and highly reliable.

SUMMARY OF THE INVENTlON The present invention is directed to providingan improved interconnection bctween a coaxial cable and a structuralmember. An elongate fitting member is inserted between an electricalconductor and its coaxially disposed braided shield and a retainingmember is fitted over the fitting member and shield. Since the internalbore of the retaining member is only slightly larger than the diameterof the fitting member and the thickness of the coaxially disposedbraided shield, there is effected a uniform tensile stress on each ofthe wires of the braided shield, thereby resulting in increasedreliability at a minimum complexity.

It is a prime object of the invention to provide an improved connectorfor a coaxial cable.

Yet another object is to provide a coaxial cable connector or reducedcomplexity.

Another object is to provide a coaxial cable connector employing itsbraided shielding as the ioad bearing member and which does notintroduce excessive, localized stress.

Still another object is to provide a connector which is readilyinstalled.

Still another object is to provide a connector suitable for electric,metallic conductors or fiber-optic conductors.

These and other objects of the invention will become more readilyapparent from the ensuing specification when taken with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isomeric exploded view ofthe invention. FIG. 2 is a longitudinal cross-sectional view ofthe invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings,there is shown a pre ferred embodiment ofa connector 10 mounted in placeon a structural member 11, such as a wall or bulkhead. The connector isso disposed to serve as an anchor point for a cable 12, the primarypurpose of which is to transfer electromagnetic energy.

The details of the connector are more clearly depicted in FIG 2 of thedrawings. Here, the cable is disposed to function as a load bearingmember for a towed sensor trailing from the left side. Conductors 13.either metallic or fiber optic, bidirectionally couple power and data toand from machinery and instrumentation at opposite ends of the cable.The conductors positioned and protected by a dielectric, fibrous packing14 are in widespread use in cables of this type. A coaxial. braidedshielding 15 covers the conductors and packing and is routinely sodisposed to serve its primary purpose, that being to prevent remotelyoriginating spurious signals from being picked up by metallic conductors13. In a secondary role. the braided shielding functions to protect theconductors and is woven in a conventional pattern from a number of alloywires. Lastly. a flexible plastic-like or rubber covering 16 ensuresthat the watertight integrity of the cable is not impaired.

Where the cable approaches structural member 11. it is first fed througha gland 17 of conventional design. A popular type of gland includes afirst lock nut threaded into the structural member. A second lock nut istightened and forces a collar into a grommet. The grommet is deformed bythe collar and is brought to bear against the outer surface of eithercovering 16 or coaxial braided shielding IS. The main purpose of thegland is to seal the connection although it docs partially act in asecondary role as a connector or a retainer of the cable.

The cable, having passed through structural member 11, now protrudesaway from its inner wall. Packing 14 is removed from the inside of aprotruding portion of coaxial braided shielding 15. With the packing removed there is now defined a cylindrically-shaped void between theshieiding and the conductors. A fitting member 18 is sized to fit withinthe cylindricallyshaped void and is shaped with a coaxial passageway forreceiving the conductors. The outer surface of an elongate portion 19 ofthe fitting member has a diamc ter being slightly in excess of the innerdiameter of coaxial braided shielding 15. When the elongate portion isinserted therein, the braided shielding lightly grips it uniformly alongits entire length. Because a first end of the fitting member is formedwith a rounded shoulder 20, it is a relatively simple matter to insertthe fitting member within the braided shielding. The configuration ofthe rounded shoulder also prevents the buildup of excessive stresseswhen the cable is under tension. At the opposite end of the fittingmember a radially extending rim 21 limits the degree of longitudinaltravel in the braided shielding and helps to engage the shield ing in amanner to be explained below.

An essentially cylindricallyshaped retaining member 22 is provided witha coaxial bore 23 having a diameter which is slightly in excess of thediameter of elongate portion 19. Since the coaxial bore is sodimensioned. a small shell-shaped space is formed within whichprotruding portion a of the braided shielding is contained to be heldadjacent elongate portion 19.

When a load pulls from left to right on cable 12, see FIG. 2, protrudingportion 150 of the coaxial braided shielding uniformly constricts alongthe outer surface of elongate portion 19 to engage the fitting memberThe resultant constricting force is uniform along the elongate outersurface and the aforedescribed rounded shoulder avoids the creation ofan area of high stress where the coaxial braided shielding engages thefitting member. Because of the shieldings gripping, the load is coupledto fitting member 18. This causes the fitting member to be pulled towardretaining member 22. Flat, opposite ends 24 of the retaining member abutagainst the inner surface wall of structural member 11 and radiallyextending rim 21 of the fitting member and the load is transferred tothe structural member.

There is no clamping of the braided shielding or otherwise uneventransfer of the load through the aforedescribed elements The ease ofassembly of the disclosed connector enables a rapid electrical couplingof the conductors to a load bearing structural member. Because of thefew easily machined parts involved, this connection is inherentlytrouble-free.

in this invention the well known high strength capabilities of finelydrawn metal alloys used as electrical shielding are utilized to functionas the load bearing member for a coaxial cable. This high strengthcapability is not compromised at the connector, due to the novelconfiguration and coaction of the disclosed invention. The soundengineering considerations embraced by this invention have produced aconnector which is more reliable and less expensive than contemporaryConnectors.

Obviously, many modifications and variations of the present inventionare possible in the light of the above teachings, and, it is thereforeunderstood that within the scope of the disclosed inventive concept. theinvention may be practiced otherwise than specifically described.

What is claimed is:

l. A secure mechanical interconnection comprising:

a wall member having an opening therethrough;

a coaxial cable having at least one axially extending conductor ofelectromagnetic energy, insulation covering said conductor, an elongatebraided conductive shielding coaxially disposed about said insulationand an elongate flexible covering coaxially carried on said shielding,said cable extending through said opening in said wall member;

a rigid elongate tubular-shaped member having an inner diameter sized tocontain and containing said conductor therethrough and further having anouter diameter sized to fit and fitting within said braided conductiveshielding in a slidable relationship, said elongate tubular-shapedmember being provided with an annular rounded shoulder at one end and aradially extending rim at its opposite end and;

a rigid cylindrically-shaped member coaxially carried on said rigidelongate tubular-shaped member by having a coaxial bore sized to fitabout said tubularshaped member and said braided conductive shielding,said cylindrically-shaped member being configured with oppositely facingends for mechanically engaging an inner surface of the wall member andsaid radially extending rim of said tubularshaped member, as a tensileforce is exerted on said coaxial cable, said braided conductiveshielding uniformly gripping said elongate tubular-shaped member alongthe surfaces defined by said outer diameter and said rounded shoulderand said radi ally extending rim bearing against one oppositely facingend of said rigid cylindrically-shaped memher to transfer the tensileforce to the wall member via the other oppositely facing end of saidrigid cylindrically-shaped member.

2. A secure mechanical interconnection according to claim 1 furtherincluding:

a gland fitting mounted in said opening of said wall member being sizedto receive and receiving said coaxial cable therethrough for ensuring awatertight interconnection.

1. A secure mechanical interconnection comprising: a wall member havingan opening therethrough; a coaxial cable having at least one axiallyextending conductor of electromagnetic energy, insulation covering saidconductor, an elongate braided conductive shielding coaxially disposedabout said insulation and an elongate flexible covering coaxiallycarried on said shielding, said cable extending through said opening insaid wall member; a rigid elongate tubular-shaped member having an innerdiameter sized to contain and containing said conductor therethrough andfurther having an outer diameter sized to fit and fitting within saidbraided conductive shielding in a slidable relationship, said elongatetubular-shaped member being provided with an annular rounded shoulder atone end and a radially extending rim at its opposite end and; a rigidcylindrically-shaped member coaxially carried on said rigid elongatetubular-shaped member by having a coaxial bore sized to fit about saidtubular-shaped member and said braided conductive shielding, saidcylindrically-shaped member being configured with oppositely facing endsfor mechanically engaging an inner surface of the wall member and saidradially extending rim of said tubular-shaped meMber, as a tensile forceis exerted on said coaxial cable, said braided conductive shieldinguniformly gripping said elongate tubular-shaped member along thesurfaces defined by said outer diameter and said rounded shoulder andsaid radially extending rim bearing against one oppositely facing end ofsaid rigid cylindricallyshaped member to transfer the tensile force tothe wall member via the other oppositely facing end of said rigidcylindrically-shaped member.
 2. A secure mechanical interconnectionaccording to claim 1 further including: a gland fitting mounted in saidopening of said wall member being sized to receive and receiving saidcoaxial cable therethrough for ensuring a watertight interconnection.